'Consciousness meter' may predict coma recoveries

Daydreaming your way out of a coma? Unlikely as it sounds, keeping track of a wandering mind may one day help doctors to discover whether a brain-damaged individual is still "in there".

When a healthy person is daydreaming, their brain is not occupied with specific tasks and the "default network", a series of specific, connected regions in the brain's cortex, kicks in. The network's purpose is still hotly debated but recent evidence suggests it keeps the brain primed and ready to take on new tasks. Problems activating the default network have been linked to cognitive diseases like Alzheimer's and schizophrenia.

Now Steven Laureys and colleagues at the University of Liège in Belgium have used brain scans to measure the activity of the default network in 13 brain-damaged people whose levels of consciousness were different.